The objective of the proposed investigation is to purify and structurally identify the pheromones released by cow Asian elephants during estrus and at ovulation. Threshold levels of pheromones in whole estrous urine, estrous vaginal secretions, estrous urine extracts, and certain chromatographic fractions elicit flehmen responses by bulls. In initial studies the number of flehmen responses served as a reliable bioassay to demonstrate the biological response by the bull elephants. Other parameters have recently been added to the bioassay to allow detection of lower levels of pheromones and to provide statistical verification. The detection of several active regions after high performance liquid chromatographic (HPLC) separation suggests that the elephant may use a multicomponent pheromone system. Active fractions separated by flash chromatography (FC), thin layer chromatography (TLC), and HPLC from estrous urine and vaginal secretions will be further purified by preparative gas chromatography (gc) and then analyzed by gas chromatography/mass spectrometry (gc/ms) to assign chemical structures. Molecular and structural identification will make possible more precise assessment of the role of such pheromones in reproductive physiology and chemical communication involving the vomeronasal organ, an organ associated with brain centers implicated in male sexuality. The identified structures could be used during artificial insemination procedures aimed at the preservation of this endangered species by planned genetic diversity. As the elephant is a highly individualistic large, long-lived land mammal with a uniquely long gestation period, an understanding of its reproductive processes has relevance to understanding mammalian and human reproduction.